ANTINEOPLASTIC V LEUKEMOGENIC EPIPODOPHYLLOTOXIN EFFECTS

描述：(申请人摘要)这项工作的目标是 更好地了解表鬼臼毒素诱导的机制 白血病的发生。表鬼臼毒素导致治疗相关 染色体11q23带MLL基因易位的白血病。 目前的证据表明，抗肿瘤和致白血病 表鬼臼毒素的作用是由于染色体的断裂和 通过染色体易位解决的断裂与 白血病。表鬼臼毒素母体化合物稳定DNA 拓扑异构酶II-DNA共价中间体，降低DNA拓扑异构酶 II-介导的宗教作用，并导致染色体断裂。这些事件 启动凋亡细胞死亡途径，理想的抗肿瘤药物 行动。 表鬼臼毒素被代谢成几种化合物，也可能 通过产生基本位点或形成染色体而导致染色体断裂 DNA加合物。申请人还假设表鬼臼毒素 因为它的代谢物可能会导致 易位，以及次生基因变化，除了 易位也可能是白血病发展所必需的。第一 新的数据支持这一假说：细胞色素的基因 代谢表鬼臼毒素母药的P-450(CYP)3A4可能 调节风险，而疾病发作的潜伏期表明 还有一些次要的变化。在目标1中，申请者将克隆MLL PANHAND变异体聚合酶链式反应检测基因组易位断裂点 系列白血病前期和白血病骨髓的建立观察 具有特定易位的细胞的克隆性。在目标2中， 申请者将直接比较依托泊苷及其代谢物的作用。 体外DNA拓扑异构酶II在MLL基因组上的裂解和定位 易位断裂点，以及骨骼中MLL基因的断裂 骨髓干细胞。在目标3中，申请者将测量依托泊苷和 患者血浆和尿液中潜在的白血病代谢物 接受治疗并同时检查染色体断裂 MLL和MLL基因易位的出现情况。 利用基因芯片技术，申请人将评估二次 携带MLL基因的治疗相关性白血病的遗传变化 目标4的实验中的易位。成功地执行了这些 特定的目标将提供关于病因、发病机制、 这种治疗并发症的自然历史和演变，并可能 推进白血病预防策略的合理设计 保护这些重要药物的抗肿瘤益处。

DESCRIPTION: (Applicant's Abstract) The objective of this work is to better understand the mechanisms of epipodophyllotoxin-induced leukemogenesis. Epipodophyllotoxins result in treatment-related leukemias with translocations of the MLL gene at chromosome band 11q23. Current evidence suggests that both antineoplastic and leukemogenic epipodophyllotoxin effects are due to chromosomal breakage and that breakage resolved by chromosomal translocation is associated with leukemia. Epipodophyllotoxin parent compounds stabilize a DNA topoisomerase II-DNA covalent intermediate, decrease DNA topoisomerase II-mediated religation and cause chromosomal breakage. These events initiate an apoptotic cell death pathway, the desired antineoplastic action. Epipodophyllotoxins are metabolized to several compounds that may also lead to chromosomal breakage by creation of abasic sites or by forming DNA adducts. The applicant hypothesizes that epipodophyllotoxin as well as its metabolites may contribute to the breakage that results in translocations, and that secondary genetic changes, in addition to the translocations may also be required for leukemia to evolve. The first hypothesis is supported by new data that the genotype of cytochrome P-450 (CYP) 3A4, which metabolizes epipodophyllotoxin parent drug, may modulate the risk, while latency to the onset of disease suggests that there are secondary changes. In Aim 1 the applicant will clone MLL genomic translocation breakpoints by panhandle variant PCR and examine serial pre-leukemic and leukemic marrows to observe establishment of clonality by cells with a particular translocation. In Aim 2 the applicant will directly compare effects of etoposide and its metabolites on in vitro DNA topoisomerase II cleavage and religation at MLL genomic translocation breakpoints, and on breakage within the MLL gene in bone marrow stem cells. In Aim 3 the applicant will measure etoposide and potential leukemogenic metabolites in plasma and urine of patients undergoing treatment and concurrently examine chromosomal breakage in MLL and appearance of MLL gene translocations in the treated subjects. Using cDNA microarray technology, the applicant will appraise secondary genetic changes in treatment-related leukemias with MLL gene translocations in experiments of Aim 4. Successful execution of these Specific Aims will provide new knowledge of the etiology, pathogenesis, natural history and evolution of this treatment complication and may advance the rational design of leukemia preventive strategies that preserve the antineoplastic benefit of these important drugs.